.alpha.-Aryl propionic acids are well known pharmaceutical compounds and include such well known analgesics such as ibuprofen, naproxen, ketoprofen, flurbifrofen and the like. Ibuprofen (Formula I) and naproxen (Formula II) are well-known non-steroidal anti-inflammatory (NSAI) drugs. ##STR1## Several processes have been developed in the past to synthesize .alpha.-aryl propionic acids. For example, U.S. Pat. No. 4,981,995 describes the synthesis of ibuprofen by carbonylating 1-(4'-isobutylphenyl)ethanol. Jean-Pierre Rieu et al., Tetrahedron Vol. 42, No. 15, 4095-4131 (1986), and H. R. Sonawane et al. Tetrahedron: Asymmetry. Vol. 3, No. 2 163-192 (1992) review several general methods of synthesis of optically active .alpha.-aryl carboxylic acids.
Optically active forms of .alpha.-aryl propionic acids have been shown to exhibit therapeutic value greater than their racemic counterparts. Thus, for example, in the case of ibuprofen, the S(+)-enantiomer has been found to be more pharmacologically active than the racemic form, A. Avgerinos et al. Chirality. Vol. 2, 249 (1990). However, most of the known processes to prepare .alpha.-aryl propionic acids in general, and ibuprofen in particular, generally result in the formation of essentially the racemic form of such acids. This necessitates an extra step of resolving the racemic form into the enantiomers by elaborate resolution processes. U.S. Pat. Nos. 4,994,604 and 5,015,764 describe resolution processes to resolve racemic ibuprofen.
Due to the commercial significance of .alpha.-aryl propionic acids, there is an identified need for better and more economically viable synthetic processes to make them. Furthermore, it will be highly desirable if such processes yield the optically active forms of such acids directly, without the need to resolve a racemic mixture.
Thus, it is an object of this invention to provide an efficient and economic process to make .alpha.-aryl propionic acids.
It is a further object of this invention to provide a process which can be utilized to make the optically active forms of such acids directly without the need to resolve the racemic mixture.